Semiconductor transistors, in particular field effect-controlled semiconductor transistors such as n-metal-oxide semiconductor field effect transistors (MOSFETs) and insulated-gate bipolar transistors (IGBTs) are used for a variety of applications, including in particular as switches in power supplies and power converters, electric automobiles, air-conditioning systems and also stereo systems.
Hitherto, power semiconductor components have been optimized principally with regard to a low on resistance (Ron) in conjunction with the smallest possible area requirement (A), in particular with regard to a low product Ron*A, fast switching and/or low switching losses. Inductive loads can generate large voltage spikes during the switching process, and power semiconductor components being driven need additionally to be protected against said spikes.
Particularly for high-power circuits, use is often made of DMOS field effect transistors, e.g. DMOSFETs (double-diffused metal-oxide semiconductor field effect transistor), the channel structures of which are produced by double implantation. Hitherto, DMOS transistors have been embodied either as planar DMOS transistors or as trench MOS transistors. The planar DMOS transistors require a relatively large amount of semiconductor area particularly in the case of relatively high reverse voltages (>30 V), which makes the products expensive. The trench MOS transistors require very much less semiconductor area, but are associated with an increased process outlay during their production, e.g. in order to provide an edge termination suitable for the voltage class. In general, in the case of the trench MOS transistors the gain in area exceeds the additional process outlay, as a result of which a cost saving is obtained overall. In the case of energy-limited and/or so-called multi-chip products (further signal pads and lines are required here in addition to the DMOS transistor), said gain in area cannot be fully utilized, however, since a certain minimum semiconductor area is required for the energy to be commutated and/or lines and pads. However, this area is expensive in the case of complex DMOS technologies.
Therefore, there is a need for improved field effect semiconductor components and improved production methods for field effect semiconductor components.